The present invention relates generally to diagnostic systems that monitor the performance of gas turbine engines, and more specifically to a multilevel digital data diagnostic system.
Turbo-jet engines use a rotary compressor whose blades compress air into a pressurized medium. This medium is combined with fuel and ignited in a combustion chamber to produce a thrust exhaust. What is interesting about these engines is the thrust exhaust of the combustion chamber is used to spin a turbine which drives the compressor, as well as to propell the jet. In the case of the turbo-jet engine, all of the work generated by the turbine is used up by the compressor and by the auxiliaries, such as the fuel pumps, generators, and oil pumps.
As mentioned above, the thrust exhaust spins a turbine which axially drives the compressor with a moment of inertial that produces resultant stresses on the compressor blades. These resultant stresses are manifested on the blade surface in the form of a tensile stress that is capable of bending the leading edge, trailing edge or the entire blade structure. The task of providing a diagnostic system that monitors the aeromechanical performance of gas turbine engines is alleviated, to some extent, by the systems disclosed in the following U.S. patents, the disclosures of which are incorporated herein by reference:
U.S. Pat. No. 4,402,054 issued to Osborne et al; PA1 U.S. Pat. No. 4,435,770 issued to Shiohata et al; PA1 U.S. Pat. No. 4,437,163 issued to Kurihara et al; and PA1 U.S. Pat. No. 4,644,479 issued to Kemper et al.
Osborne et al disclose a monitoring apparatus capable of automatically diagnosing a system malfunction with some degree of probability. Shiohata et al disclose aparatus for diagnosing vibration in a rotor of a rotary machine. The apparatus generally includes sensing means for sensing and providing an output indicative of rotation of a rotor, a detector for detecting vibration at each of several locations along the rotor shaft and providing an output representative of a vibration, and means to analyze the outputs, compare the analyzed outputs with reference values, calculate abnormal vibration components, and compare the abnormal vibration components with previously obtained values at the same measuring locations. Kurihara et al disclose apparatus and methods somewhat similar to those disclosed by Shiohata et al.
Finally, Kemper et al disclose diagnostic apparatus to monitor a steam-turbine generator power plant. The apparatus includes a plurality of sensors to monitor and provide an output of a parameter, and control means operable to establish a first, second and third subsystem responsive to sensor signals. The sensor signals provide an output of change in sensor readings, validated conclusions with a certain confidence factor responsive to selected one of the change indications, and validated conclusions relative to sensor signals, respectively.
While the above-cited references are instructive, the need remains to provide an active digital classifier system that constantly monitors and diagnoses the aeromechanical performance of gas turbine engine systems. The present invention is intended to satisfy that need.